In order to achieve a two-axis or a three-axis magnetic compass chip, it is necessary to employ highly sensitive X-axis and Y-axis magnetic field sensors at the same time in the device. Magnetoresistive sensing units generally are sensitive to a magnetic field applied in a single direction. For a magnetoresistive bridge sensing unit structure, the bridge should only respond as the magnetic field changes to a magnetic field applied in an X direction, and the bridge should have no response when a magnetic field is applied in a Y direction. To improve magnetic field sensitivity, a push-pull bridge is often employed, where a push arm and a pull arm are located on separate chips, wherein one chip is rotated 180 degrees relative to the other, and the chips of the push arm and the pull arm are then connected using wirebonds.
The above-mentioned Y-axis magnetoresistive sensor has the following problems: the push arm and the pull arm cannot be manufactured on a single substrate; the wirebonding process for connecting the discrete chips increases the process complexity; and the measurement accuracy of the sensor is degraded.